Protein-Supported RuO2 Nanoparticles with Improved Catalytic Activity, In Vitro Salt Resistance, and Biocompatibility: Colorimetric and Electrochemical Biosensing of Cellular H2O2.

Protein-supported nanoparticles have a great significance in scientific and nanotechnology research because of their "green" process, low cost-in-use, good biocompatibility, and some interesting properties. Ruthenium oxide nanoparticles (RuO2NPs) have been considered to be an important member in nanotechnology research. However, the biosynthetic approach of RuO2NPs is relatively few compared to those of other nanoparticles. To address this challenge, this work presented a new way for RuO2NP synthesis (BSA-RuO2NPs) supported by bovine serum albumin (BSA). BSA-RuO2NPs are confirmed to exert peroxidase-like activity, electrocatalytic activity, in vitro salt resistance (2 M NaCl), and biocompatibility. Results indicate that BSA-RuO2NPs have higher affinity binding for 3,3',5,5'-tetramethylbenzidine or H2O2 than bare RuO2NPs. Moreover, BSA turns out to be a crucial factor in promoting the stability of RuO2NPs. Taking the advantages of these improved properties, we established colorimetric (linear range from 2 to 800 μM, a limit of detection of 1.8 μM) and electrochemical (linear range from 0.4 to 3850 μM, a limit of detection of 0.18 μM) biosensors for monitoring in situ H2O2 secretion from living MCF-7 cells. Herein, this work offers a new biosynthesis strategy to obtain BSA-RuO2NPs and sheds light on the sensitive biosensors to monitor the H2O2 secreted from living cells for promising applications in the fields of nanotechnology, biology, biosensors, and medicine.